1. Field of the Invention
The present invention relates to a cutting fluid tank used for a machine tool such as a machining center and a turning machine.
2. Description of the Background Art
For example, in a machine tool configured to perform a cutting work such as a machining center and a turning machine, cutting fluid is generally used for a purpose of lubrication and cooling of tools and discharge of chips.
The cutting fluid discharged toward a work chamber of the machine tool by a cutting fluid supply pump is discharged to outside the work chamber together with chips scraped out from the work. The discharged cutting fluid flows into a tank body of a cutting fluid tank and stores temporarily after the chips mixed therein have been separated and removed by a chip conveyor or a filter, and is supplied therefrom to the work chamber again by the cutting fluid supply pump.
However, the chips mixed in the cutting fluid cannot be separated and removed by 100% depending on the chip conveyor or the filter, and some quantity of chips flow into the tank body of the cutting fluid tank together with the cutting fluid. However, if the chips entered the tank body are sucked into devices such as the cutting fluid supply pump, the devices may be damaged or may break down.
In addition, the chips flowed together with the cutting fluid are gradually accumulated in the tank body, whereby an effective capacity of the tank body, that is, a capacity for storing the cutting fluid itself is reduced. Therefore, when a large quantity of the cutting fluid is supplied toward the work chamber, a problem of exhaustion of the cutting fluid in the interior of the tank body may arise.
In addition, the chips are settled and accumulated on a bottom portion of the tank body, the state and the quantity of accumulation are difficult to figure out at first glance and a lot of time and effort are required for removing the accumulated chips.
Accordingly, installing chip separating apparatus such as a centrifuge or a magnet separator in a predetermined position in the interior of the tank body and separating and removing the chips from the cutting fluid are performed.
However, the chips contained in the cutting fluid are spread over the entire area of the tank body, and is settled and accumulated on the bottom portion thereof. Therefore, even though an attempt is made to collect the chips by the chip separating apparatus, only part of the chips existing in a peripheral area of the apparatus. Therefore, the chips accumulated in other areas in the tank body cannot be collected.
If a flow of the cutting fluid in the interior of the tank body is fast, since the chips mixed in the cutting fluid move with the flow of the cutting fluid, accumulation of the chips on the bottom portion of the tank body may be prevented or alleviated. However, since the quantity of the cutting fluid flowing in the tank body varies in accordance with the quantity of the cutting fluid required for machining of the work, there are cases where a flow rate is not stable and becomes slow or where the flow is stopped.
In addition, the tank body of the cutting fluid tank is required to secure a maximum capacity with respect to an installation space, and in addition, the devices such as the chip conveyor are disposed in many cases, a structure or a shape is subject to various restraints. Therefore, a narrow portion which is complex and indented portions are formed in the interior of the tank body. Consequently, there arises a problem that the cutting fluid containing the chips stays in such portions and thus the chips are accumulated on the bottom portion.
In the related art, several devices configured to prevent the chips from accumulating in the tank body of the cutting fluid tank are proposed.
For example, a cutting fluid tank described in JP-UM-A-6-42045 includes in a tank body: a central separating plate configured to partition the interior thereof into a front part and a rear part, chip trapping pocket located at one corner portion, and two front and rear movable plates movable along both sides of the central separating plate along the central separating plate. Each of the movable plate includes a nozzle configured to eject cutting fluid so as to form a circulating flow of the cutting fluid in the interior of the tank body, and a scraping plate configured to scrape chips accumulated on a bottom portion of the tank body.
JP-UM-A-4-42350 discloses a cutting fluid tank configured to eject the cutting fluid pumped up from the interior of the tank body through the nozzle so as to run along a wall surface of the tank body to form an eddy current in cutting fluid in the interior of the tank body, so that chips are prevented from accumulating on a bottom portion of the tank body. JP-UM-A-7-7855 discloses a cutting fluid tank having the same configuration as JP-UM-A-4-42350. However, in the cutting fluid tank of this disclosure, chips collected at a center portion of a tank body by an eddy current are pumped up with a pump with cutting fluid, and causes the pumped cutting fluid containing the chips to pass through a filter and to be returned again to the tank body.
In JP-A-2004-114221 and JP-A-2-106248, installing a screw for stirring cutting fluid in an interior of a tank body of a cutting fluid tank to prevent chips from accumulating on
a bottom portion of the bank body is disclosed.